Integrate Yarn with maven profiles
So the yarn-related projects are only imported if building a stratosphere with yarn (hadoop2).

- Remove the cloudera repository from our main pom: It is considered as bad practice to refer to other dependencies outside of maven central. Out project can now be build completely from maven central.
- pact-hbase now uses a different hbase version (I only changed the minor version). But we can not use the "cdh" version anymore. Since there are no tests for hbase, I can not validate if everything is still working.